Suppose a New Metallic Element X Is Discovered,and Its Reactions

question 80

Multiple Choice

Suppose a new metallic element X is discovered,and its reactions with oxygen gas and chlorine gas at 298 K are studied. Trial
Reaction
ΔHº_rxn (kJ/mol)
1
4X(s) + 3O₂(g) → 2X₂O₃(s)
-600
2
2X(s) + 3Cl₂(g) → 2XCl₃(s)
-800
3
4XCl₃(s) + 3O₂(g) →X₂O₃(s) +6Cl₂(g)
-200
However,it is later discovered that one of the samples was contaminated,and the ΔHº_rxn value from this trial is not reliable.Which trial had the contaminated sample,and what should the correct value of ΔHº_rxn be for this trial?

• A)Trial 1 had the contaminated sample; its ΔHº_rxn value should be -900 kJ/mol.
• B)Trial 2 had the contaminated sample; its ΔHº_rxn value should be +100 kJ/mol.
• C)Trial 3 had the contaminated sample; its ΔHº_rxn value should be -1000 kJ/mol.
• D)Trial 3 had the contaminated sample; its ΔHº_rxn value should be +1000 kJ/mol.
• E)Not enough information is provided; all three trials must be redone.

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